Microbiology Exam 2
The base sequence of a messenger RNA molecule that is complementary to the sequence CGTTAGA would be expressed as:
GCAAUCU
How do you sterilize toxoid preparation for immunization
Gamma rays
Sometimes called "the clap"
Gonorrhea
A biological safety cabinet usually filters the air with a __________ filter
HEPA
The principal effect of ultraviolet light on bacterial cells takes place:
in the DNA of the cell
A period of 2 hours at 160°C is required for the destruction of bacterial spores:
in the hot-air oven
Heavy metals generally kill microorganisms by
inactivating enzymes and structural proteins
The spectrum of activity of tetracycline antibiotics
includes Rickettsia and Chlamydia
Bacteriocins are proteins that:
inhibit or kill other bacteria.
Chloramphenicol is a broad-spectrum antibiotic that:
interferes with peptide bond formation in microorganisms.
Cephalosporins act by:
interfering with cell wall synthesis.
The halogen common to Wescodyne and Betadine:
is iodine in a form known as iodophor
A substance that has been pasteurized
is not necessarily sterile.
Point mutations:
it affects a base pair. it may be a change to a different base pair. it may be a substituted base pair
All the following are true of the bacterial chromosome, except:
it contains the plasmids
Filtration is very different from heat or radiation methods because:
it is a physical separation method rather than a sterilization method
An antibiotic is useful in
killing environmental competitors
AKA Hansen disease
leprosy
All the following are essential to the process of DNA replication, except
mRNA
The most common filtration method uses the
membrane filter
Mercury is rarely used in antiseptics in the modern era because
mercury is very toxic to body tissues
Sulfonamides can interfere with the ______ of bacteria because they are similar to _____.
metabolism, PABA
All of the following are true about DNA repair mechanisms, except
mismatch repair involves replacing long sequences of DNA.
A phenol coefficient (PC) higher than 1 indicates a chemical is:
more effective than phenol.
Tetracyclines such as doxycycline are currently the drugs of choice for treating:
most rickettsial and chlamydial diseases
Besides HGT, __________ is another way to permanently alter the genetic material in a bacterial cell.
mutation
Isoniazid inhibits the production of
mycolic acid
The stop codon in an mRNA codes for
no amino acid
The tRNA anticodon TTT would pair up with the codon
no such anticodon exists
How many origins of replication are there in every bacterial DNA molecule?
one
Tetracycline antibiotics are associated with
discoloration of the teeth
Triclosan destroys bacteria by
disrupting cell membranes.
All the following function in the process of protein synthesis, except
electron transport
Clinically important antibiotics in the macrolide group are:
erythromycin and clarithromycin.
A person who is allergic to penicillin may be treated with
erythromycin, but not ampicillin
Chaperones are proteins that
facilitate proper folding of polypeptides
plasmids contain over 50% of the total genetic information of a bacterial cell
false
Bacterial polypeptides will start with the amino acid
formylmethionine (fmet).
Energy wavelengths less than 1 nm are associated with
gamma radiation
Penicillin antibiotics are used primarily against
gram positive bacteria
The aminoglycoside drugs like gentamicin are widely prescribed for treatment of:
gram-negative bacterial infections.
The major side effects of therapy with chloramphenicol include:
gray syndrome
One of the Streptococcus pneumoniae strains used by Griffith was called smooth because the cells
had a smooth capsule
A bacterial cell that is transduced
has acquired bacterial DNA from a virus
Pasteurizing milk for 30 minutes at 63°C is called the __________ method.
holding (batch)
Genetic recombination that involves the lateral intercellular transfer of DNA from a donor cell to a recipient cell is called
horizontal gene transfer (HGT).
The tubercle bacillus is usually susceptible to
rifampin, but not penicillin.
F factors replicate the DNA using the
rolling circle mechanism
Antibiotics are an example of a
secondary metabolite
Antibiotics represent compounds not directly used for growth and reproduction called:
secondary metabolites.
A new DNA molecule can be produced by
semiconservative replication
______ is a condition in which microbes or their toxins are present in tissues or the blood.
sepsis
One drop of 1% solution used to prevent gonorrhea in newborns
silver nitrate
One of the limitations of the autoclave is that:
some plasticware melts in the high heat.
The origin of the penicillin-resistant strain Neisseria gonorrhoeae probably is due to:
spontaneous mutation
Mutations arising from chance events in the environment are known as
spontaneous mutations
Messenger RNA contain
start and stop codons
___________ refers to the destruction of all forms of microbial life
sterilization
In the operon, genes that code for proteins are called:
structural genes
Side effects attributed to tetracycline antibiotics include:
stunted bones and discolored teeth.
Antimicrobial agents designed and developed in the research laboratory are called
synthetic drugs
children affected with this STD can develop Hutchinson's triad
syphilis
forms a gumma
syphilis
The effects of Hutchinson's triad, a possible complication of congenital syphilis, are observed in the
teeth, eyes and ears
Ultraviolet light is valuable for reducing the microbial population in:
the air of a hospital room
The chemotherapeutic index refers to a drug's:
toxic and therapeutic doses.
If boiling water is used to destroy microorganisms, it is imperative that
traces of organic matter be removed
The production of RNA using DNA as a template is known as:
transcription
Requires the intervention of a virus.
transduction
DNA from the environment enters a recipient cell.
transformation
May follow a release of DNA fragments from a dead cell
transformation
Was first observed in pneumococci by Griffith
transformation
Isoniazid is a narrow-spectrum antibiotic that is useful for treatment of:
tuberculosis
The passing of genes from parent cells to daughter cells is called
vertical gene transfer
Chlorhexidine is a phenol derivative used to
wash hands and clean wounds superficially
When food has been salted
water diffuses out of microorganisms, causing them to shrivel.
An antibiotic that affects Staphylococcus, Escherichia, and the mycobacteria would be considered a drug:
with a broad spectrum
All of the following apply to phenol
-Its activity is reduced in the presence of organic matter. -Joseph Lister first used it in the 1860s. -It is the standard disinfectant against which others are evaluated
If an mRNA sequence is AUGGCCGACUGA, then the inactive DNA strand sequence must be:
ATGGCCGACTGA
Which of the following is not part of chain termination during translation?
AUG codon
Can induce human tumors and is highly explosive
Ethylene oxide
Used in the sterilization of plastics
Ethylene oxide
Which chemical would be a sterilization method for plasticware that cannot be heated?
Ethylene oxide gas
a conjugation pilus is produced by
F+ cells
Intermittent sterilization is done at ___________ for __________ minutes for __________ successive days.
100ºC; 30; 3
In an autoclave under 15 lb/in2 steam pressure, the approximate temperature will be
121.5°C
If a complete bacterial mRNA contains 3,000 codons, how many amino acids will exist in the protein produced?
2,999
The mRNA that codes for a particular protein will have ___ nucleotide(s) for each amino acid in the protein
3
The conditions necessary to kill Mycobacterium tuberculosis by pasteurization are:
30 minutes at 63°C.
How many genes are in Escherichia coli?
4,300
Example of base analog
5-bromouracil
One of the difficulties in controlling the spread of gonorrhea is that
50% of female infections may be asymptomatic.
HEPA filters prevent which percentage of particles from escaping as aerosols into the laboratory air?
99%
Both bacitracin and polymyxin B are synthesized by _____. They are quite toxic internally and can cause kidney damage. Therefore, they generally are restricted to topical use, such as on the skin.
Bacillus species
How can a 1.5-mm long, circular chromosome fit into a 1.0- to 2.0-µm E. coli cell?
By supercoiling, a twisting and tight packing Packing caused by nucleoid-associated proteins DNA double helix twists on itself like a wound-up rubber band
This STD is called soft chancre
Chancroid
Bacteriocin
Chemical produced by bacteria that kill other bacteria
______ is a very small mycoplasma that causes urethritis. It can be treated by azithromycin.
Chlamydia trachomatis
The less-common STD caused by Chlamydia trachomatis
Chlamydial urethritis
Tissues samples contain reticulate bodies
Chlamydial urethritis
Which chemical agent burns skin and eyes on contact?
Chlorine dioxide
Plasmid
Closed circular DNA, with few genes, nonessential to the cell
plasmids are composed of
DNA
enzymes involved with excision repair in DNA
DNA ligase DNA polymerase Nucleases
The enzyme responsible for the synthesis of DNA from a DNA template is called
DNA polymerase
The quinolones are synthetic drugs that block _______ and are used to treat urinary tract infections, gonorrhea and chlamydia, and intestinal tract infections.
DNA synthesis
How are antiseptics and disinfectants different?
Disinfectants are used on objects, whereas antiseptics are used on living tissues.
DNA ligase
Enzyme that seals DNA fragments together
Why is the genetic code considered redundant?
In most cases, there is more than one codon for each amino acid.
A halogen often used as a tincture for wounds
Iodine
What does an F plasmid do
It allows for the transfer of genetic material from a donor to recipient cell through a recombination process.
During transcription, how many DNA strands in a gene are transcribed?
One strand
Armes test
Procedure to screen chemicals for mutagenic properties
Which one of the following bacteria is not related to a sexually transmitted disease?
Pseudomonas aeruginosa
What are resistance factors known as?
R plasmids
UGA, UAG, and UAA are what type of codons?
Stop codons
Mutagen
Substance that induces change in DNA bases
Which of the following does not apply to plasmids?
They are essential for growth
What is an insertion sequence (IS)?
a small segment of DNA with about 1,000 base pairs
Which of the following types of RNA function to bring the amino acids to the ribosome for assembly into a polypeptide chain?
Transfer RNA
Prokaryote genome studies have shown that genes involved with the same process are clustered. This makes genetic control more efficient because their activity can be coordinated within one cluster.
True
Watson and Crick worked out the structure of DNA using Rosalind Franklin's X-ray crystallography.
True
Base pair insertion
Type of mutation that produces a reading frameshift
Another method, known as the __________ method, uses a temperature of ___________ for 3 seconds.
UHT; 140ºC
Radiations with wavelengths between 100 nm and 400 nm are considered:
UV light
Nonionizing radiations are typified by:
UV rays
How do you sterilize a table top in a laboratory?
Ultraviolet light
_______ has emerged as a key treatment in therapy for gram-positive organisms that are resistant to other antibiotics; it is often is referred to as the "drug of last resort
Vancomycin
The similarities between organisms and symptoms have led many microbiologists to believe there is a relationship between:
Yaws and syphilis
The deletion or insertion of nucleotides during chromosomal replication most likely would cause
a "reading frameshift" mutation
Mutation
a change in DNA base sequence
Trachoma or chlamydial opthalamia is
a disease of the eye causing blindness in 7 to 9 million people worldwide.
Which of the following could not be sterilized by the autoclave?
a laboratory table
What happens in semiconservative DNA replication?
a new strand of DNA with bases complementary to a parent strand combines with a parent strand to form the double helix.
Sterilization by intermittent sterilization requires:
a period of 3 days
Both the cephalosporin and penicillin antibiotics:
act on the cell wall of bacteria.
HEPA filters are used to filter which one of the following
air
Copper has its principal activity against
algae
The two major drawbacks to the use of natural penicillins are:
allergic reactions and development of drug-resistant bacteria.
Detergents display their antimicrobial ability by:
altering the cell membrane and causing cell lysis.
Genes existing on plasmids may include those for:
antibiotic resistance
Gonorrhea caused by which of the following has recently been observed?
antibiotic-resistant strains
The hot-air, or oven, method of sterilization is useful for those items that:
are dry or do not mix with water.
Sulfanilamide is highly active against those bacteria that:
are gram-positive
A common feature of bacitracin and polymyxin B is that both antibiotics
are only used topically.
All aminoglycoside antibiotics function by:
attaching to bacterial ribosomes and causing a misreading of the genetic code.
A(n) __________ is a high-pressure device in which steam is superheated under pressure to kill microbes in about 15 minutes
autoclave
An advantage of the membrane filter is that:
bacteria multiply and form colonies on its surface, where they can be studied
Ethyl alcohol has virtually no effect on:
bacterial spores
A plasmid may carry information for
bacteriocin synthesis. transfer of genetic material. antibiotic resistance.
Low temperature is
bacteriostatic
Termination factors:
bind to the mRNA site at the ribosome.
Ultraviolet light may induce a mutation by
binding together adjacent thymine molecules on the DNA molecule.
Salpingitis, a possible complication of gonorrhea, is observed as a(n)
blockage of fallopian tubes
Tetracycline antibiotics are a ________ spectrum antibiotic
broad
How do transposable genetic elements cause mutations?
by interrupting the coding sequence in genes, thereby often resulting in no protein being produced.
Characteristics of gonorrhea bacteria
diplococcus, small cell, gram negative, nonmotile
Transposons are movable genetic elements that
carry information such as antibiotic resistance from one gene location to another
Nitrous acid
chemical mutagen
Gray syndrome sometimes occurs in newborns as a serious side effect of _______.
chloramphenicol therapy
Can be used to disinfect municipal water supplies and swimming pools
chlorine
Which of the following elements would be classified as a halogen?
chlorine
Griffith's experiments used species of
coccus
Iodophors are
complexes of iodine and detergents that release iodine over long periods of time.
Deafness; impaired vision; and notched, peg-shaped teeth are a result of
congenital syphilis
Commonly involves F factor transfer.
conjugation
F factor transfer converts the recipient to F+.
conjugation
Involves DNA replication by the rolling circle method
conjugation
Requires contact between donor and recipient cells.
conjugation
involves an hfr cell
conjugation
Hfr cells are involved in
conjugation with F- cells
Nitrous acid can cause a chemical mutation by
converting DNA's adenine to hypoxanthine.
For UV light to kill microorganisms
direct exposure must take place
A method of preserving food that depends upon osmosis is
dehydration
Moist heat kills microorganisms by:
denaturation
The organism that causes gonorrhea
dies quickly and is rarely contracted from a dry surface such as toilet seat.
Parts of the operon
operator structural genes promoter
When food is dehydrated through salting, the process of water loss is called
osmosis
Pseudomembranous colitis is a condition of the intestine that may be related to:
overuse of lincomycin and clindamycin.
__________ is used to remove pathogens from milk and dairy products.
pasteurization
One drawback to the use of ultraviolet light as a sterilizing agent is its failure to
penetrate liquids or solids
The beta-lactam nucleus is the basic structure of:
penicillin
Beta-lactamase converts _____ to ______, which has no effect on the bacterial cell wall.
penicillin to penicilloic acid
Some bacteria produce beta-lactamases, which break down and inactivate
penicillins
Penicillins interfere with the synthesis of
peptidoglycan
Gonorrhea under some circumstances can spread to the
pharynx
The F factor in a bacterium is actually a
plasmid
The string of ribosomes all translating the same mRNA is called a:
polyribosome
Silver nitrate was used to
prevent gonorrhea in the eyes of newborns.
Sulfonamide is a competitive inhibitor that interferes with the ability of a bacterium to:
produce folic acid
The major activity of transcription is to
produce mRNA molecules
Members of the genus Streptomyces
produce many well-known antibiotics
Which group of antibiotics blocks DNA synthesis in bacteria?
quinolones
Gonococcal proctitis is an inflammation of the
rectum
Using a prevacuum stage in the autoclaving process can effectively
reduce the time to achieve sterilization
phages lyse bacterial cells by
replicating within them
Okazaki fragments form during
replication of the bacterial chromosome
Tetracycline antibiotics are used for
rickettsial and chlamydial diseases
Which of the following is the most efficient method for sterilization of a bacteriological loop?
the direct flame
What type of genetic information is needed in IS?
the genetic information for enzyme transposase, which is needed to move the IS to a new location in a DNA molecule.
In the microwave oven, the energy of microwaves is converted to:
the heat of friction
All the following apply to the process of protein synthesis, except
the mRNA sequence is the same as that on the DNA template strand.
Before alcohol is used for disinfection purposes:
the object to be treated must be carefully cleaned.
The pasteurization method using 140°C for 3 seconds is called:
the ultra high temperature (UHT) method.
The lowest temperature at which a microorganism is killed in 10 minutes is called the:
thermal death point
__________ is the minimum amount of time required to kill microorganisms at a given temperature.
thermal death time
This type of radiation induces adjacent __________ nucleotides in DNA molecules to bind to one another, forming dimers.
thymine
One environmental mutagen is ultraviolet (UV) light. It exerts its mutagenic effect by forming a(n) __________ in the DNA
thymine dimer
Gonococcal symptoms in a male
tingling sensation in the penis, painful urination, discharge of a yellow, thick fluid